Problem: If $x \bigtriangledown y = x+5y$ and $x \triangleleft y = x(y-6)$, find $(-1 \triangleleft -6) \bigtriangledown 1$.
Explanation: First, find $-1 \triangleleft -6$ $ -1 \triangleleft -6 = -(-6-6)$ $ \hphantom{-1 \triangleleft -6} = 12$ Now, find $12 \bigtriangledown 1$ $ 12 \bigtriangledown 1 = 12+(5)(1)$ $ \hphantom{12 \bigtriangledown 1} = 17$.